Veritas Dynamic Multipathing

Veritas Dynamic Multi-Pathing (DMP) provides the multi-pathing capability to the native devices on the system. DMP creates DMP metadevices (DMP nodes) to represent all the device e paths to the same physical LUN.

How DMP works

– VxVM uses the DMP metanodes (DMP nodes) to access disk devices connected to the system. For each disk, DMP maps one node to the set of paths that are connected to the disk. The raw and block devices are created in directories /dev/vx/rdmp and /dev/vx/dmp respectively.

Setting the naming scheme

Depending on the naming scheme you have in VxVM, device names for disks are assigned. There are 2 naming schemes available :

You can set I/O policies to distribute the load across multiple paths the storage array. The I/O policies are recorded in the file /etc/vx/dmppolicy.info. Do not edit this file manually. The I/O policies that can be configured are :

adaptive
balanced
minimumq
priority
round-robin
singleactive
To set the required policy on an array :

# vxdmpadm setattr enclosure enc1 iopolicy=[policy]
To display a set policy on the enclosure :